Add command to get detailed info about the queue

[TimJentzsch]

To make it easier to balance a sub's upvote filters and help the engagement team to select new subreddits, we should add a !queue command that displays detailed information about the state of the queue.

It could work similarly to the /queue command on Discord, but go a lot more into detail. We could highlight the subs that get the most posts into the queue, the subs that barely get posts, do a breakdown of the percentage of completed posts per subreddit, etc.
The command could also show stats for the last 7 days instead of only showing the current status.